Loom check strap



23, E959 R. L. $PR1NGFEELD 34185273 LOOM CHECK STRAP Filed June 21, 1968 INVENTOR ROBERT L. SPRiNGFIELD ATTORNEYS United States Patent M 3,485,273 DOOM CHECK STRAP Robert L. Springfield, 106 Galphin Drive, Greenville, S.C. 29609 Filed June 21, 1968, Ser. No. 739,059 Int. Cl. D03d 49/40, 41/00 US. Cl. 139-161 5 Claims ABSCT OF THE DISCLOSURE A check strap for a loom picker stick formed of multiple thicknesses of natural leather has a U-shaped portion tapering downwardly and inwardly at each end thereof for accommodating a picker stick, and is formed by impregnating the leather with a liquid polymeric composition comprising a resin and then subjecting same to pressure and a curing temperature while upon an elongated tapered form.

This invention relates to an improved loom check strap, wherein a tough check strap, resistant to moisture and possessing improved wear and more nearly uniform friction characteristics has tapered ends accommodating a picker stick in forward and rear positions.

Heretofore, check straps have been constructed from multiple thicknesses of leather sheets by adhesively securing broad fiat pieces of tanned natural leather together and then cutting strips out of the sheets of leather and splicing the ends. It was sometimes the practice to sew the thicknesses together entirely thereabout in order to effect the necessary fastening of one thickness to the other, and in order to fasten the ends of the loop comprising the check strap together. It is standard practice to secure the ends of the loop together either by a butt or tapered splice. Check straps, such as that illustrated in US. Letters Patent No. 3,288,174 issued Nov. 29, 1966, in the name of Chester R. Messer, constructed of nylon and impregnated with a polyurethane resin have met with limited success. Such check straps have been constructed of multiple thicknesses and sewn together as described above. Such check straps have also been immersed in a liquid polyurethane resin and subjected to the application of heat and pressure upon a tapered form. The inner and outer sides of such nylon check straps, however, produce widely varying amounts of friction until they become worn smooth at which time the friction drops off. Such check straps are difficult to process, do not compress readily, and the liquid polyurethane does not penetrate effectively.

Accordingly, it is an important object of this invention to provide a long lasting check strap which provides more nearly uniform friction characteristics.

Another important object of the invention is to provide a check strap capable of withstanding the action of modern high speed looms for extended periods of time, thus reducing loom downtime.

Another important object of the invention is the provision of an improved wear and moisture resistant check strap which can be produced with a minimum expenditure of labor.

Still another object of the invention is to produce an improved check strap affording better boxing and checking resulting in less seconds.

The construction designed to carry out the invention will be hereinafter described, together with other features thereof.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing forming a part thereof, wherein an example of the invention is shown and wherein:

FIGURE 1 is a perspective view illustrating a check 3,485,273 Patented Dec. 23, 1969 strap constructed in accordance with the present invention,

FIGURE 2 is a perspective view illustrating an initial step in the manufacture of the check strap illustrated in FIGURE 1,

FIGURE 3 is a perspective view, at a reduced scale, illustrating an impregnation step employed in the construction of the check strap.

FIGURE 4 is a perspective view illustrating a step of applying heat and pressure in the construction of a check strap in accordance with the present invention, and

FIGURE 5 is a front elevation, at a reduced scale, illustrating a check strap constructed in accordance with the invention upon a loom, with parts omitted.

The drawing illustrates a check strap for a loom picker stick having a closed elongated loop of multiple thicknesses of natural leather having fibers with interstices therebetween. An adhesive medium A secures the thicknesses of leather so that the outer surface of one thickness is bonded to the inner surface of another such thickness. The loop defines at each end a U-shaped portion B formed or tapered downwardly and inwardly accommodating a picker stick in forward and rear positions. A relatively long vertical intermediate portion C joins the U- shaped portions. A cured thermosetting resin impregnated within the interstices of the leather loop forming smooth side surfaces D of the loop seealed against entry of moisture into the leather extends the full breadth and entirely about said loop. The loop is compressed and densified and possesses at any location thereon a density and hardness substantially greater than that of natural leather. The U-shaped and intermediate portions and side surfaces are set therein by applying a liquid polymeric composition comprising a resin to leather while the leather is in a sufficiently natural or raw state so that said resin penetrates into said leather. The loop is subjected to curing conditions while upon an elongated tapered form E. The form is tapered on both ends converging downwardly conforming, respectively, to the position of a loom picker stick in forward and rear positions. The form has substantially fiat vertical sides joining said ends.

The closed loop is formed of multiple thicknesses 10 and 11 of natural leather. FIGURE 2 illustrates a mode of forming a closed loop of natural leather by first cutting a strip 10 formed of one thickness and tapering its ends as at 10a and 10b with conforming tapers. The adhesive 12 is applied to the ends 10a and 10b to form a splice in the thickness 10. A similar but slightly larger loop is formed of the thickness 11 and an adhesive (not shown) is applied to the inner surface thereof. As illustrated in FIGURE 1, the splice 13, which is similar to the splice formed at 10a and 10b, is positioned on the opposite sides of the loop from the first mentioned splice. The adhesive may be of any suitable type as used heretofore, to join thicknesses of leather in the construction of a check strap. Preferably, the adhesive is allowed to set upon a form upon which the leather is stretched sufficiently to promote bonding and setting of the adhesive.

The loop thus formed is then immersed in a liquid polymeric composition which comprises a resin preferably of the thermosetting variety. Thus, the resin is applied to the tanned leather while in a natural or raw state so that the interstices between the leather fibers are sufliciently open to permit substantial penetration of the resin into the leather. Preferably, using the liquid polymeric composition described below, the loop remains immersed for about forty-five minutes. While immersion, as described above is preferable, and is carried out preferably to the extent that the resin penetrates uniformly throughout the leather, it may be possible to apply the resin composi- 3 tion by brushing or spraying, or by any other suitable means before or after compression described below so long as substantial impregnation occurs. At this time the sides of the loop are vertical as shown all the way around. I

The liquid polymeric composition preferably includes a resin and a curing agent therefor so that the resin composition is thermosetting in nature. A polyurethane resin has been found to produce especially desirable results. One such polyurethane composition which has been found acceptable includes a pigmented polyester having a wet weight of 43.42 out of 100 of which .42 is zinc octolate and 8% is ethyl acetate. The composition also includes a polyisocyanate 7.56 parts which is 75% ethyl acetate. An amine in the form of ethyl diethanolamine in the amount of .24 part. An ester solvent in the form of ethyl acetate is added in an amount of 48.78 parts to make up 100. While a resin of the polyurethane type is thought to be preferable, it may be possible that another type of resin, such as an epoxy resin with curing agent may be used.

By referring to FIGURE 3 it will be noted that the liquid level L within the tank 15 is preferably above the loop so that it is totally immersed. The polyester is cured by the polyisocyanate curing agent, preferably by applying heat, and it is preferred that pressure accompanies the application of heat. The heat and pressure acting as described below, form smooth side surfaces D. FIGURE 4 illustrates apparatus for accomplishing this, and includes the use of an elongated tapered form E.

The form E is tapered on both ends as at 16, and is curved to correspond to the end portions B of the check strap illustrated in FIGURE 1. The form converges downwardly at its ends to produce tapered ends, as illustrated at B in FIGURE 1. The form has substantially fiat vertical sides 17 joining the U-shaped end portions of the form as at 17. A surface 18 is provided having a more pronounced taper at its ends and being tapered inwardly rather than being flat in the intermediate portion therebetween. Such surface forms a guide for positioning the loop within a second form 19 adapted to receive and conforming to the first mentioned form E.

The form E is pressed upon the leather by means of an air cylinder 20 which carries a piston rod 21 secured to a stop 22 which carries the form E and engages the form 19 on its downward stroke. Suitable guide members 23 are provided for moving the form E downwardly on a predetermined path for exerting even pressure of about 3,500 pounds total upon the loop placed within the cavity 19a within the form 19. The cavity is of slightly less depth than the width of the loop affording some compression vertically. Preferably, the form E and the form 19 are heated by applying electrical energy to resistance elements (not shown) contained therein, and providing same with variable thermostats and the like, for maintaining a uniform predetermined temperature of about 200 to 250 Fahrenheit for about 90 to 45 seconds, respectively.

If desired, a timer may be used with means for automatically raising the form E at the completion of a cycle. The form E is preferably slightly larger in its upper portion to take a substantial amount of the stretch out of the strap. The resin improves the tensile strength. It has been found that the leather retains about one ounce of solids from the polyurethane bath after heating, and is compacted about of an inch in thickness, and about of an inch in width.

FIGURE illustrates the check strap illustrated in FIGURE 1 accommodating the picker stick 24 being shown in solid lines in rear position, and in forward position in broken lines. The check strap would be carried within the usual brackets (not shown) for applying friction for checking the motion of the loom at desired intervals during weaving.

While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be under stood that changes and variations may be made without departing from the spirit or scope of the following claims.

What is claimed is:

1. A checkstrap for a loom picker stick including: a closed elongated loop of multiple thicknesses of leather having fibers with. interstices therebetween; means securing the thicknesses of leather together so that an outer surface of one thickness is secured to an inner surface of another such thickness; said loop defining at each end a U-shaped portion tapering downwardly and inwardly accommodating a picker stick in forward and rear positions thereof; a relatively long vertical intermediate portion between the U-shaped portions; and a cured thermosetting resin impregnated within interstices of the leather loop forming smooth side surfaces of the loop sealed against entry of moisture into the leather extending the full breadth and entirely about said loop; said loop being compressed and densified and possessing at any location thereon a density and hardness substantially greater than that of natural leather; said U-shaped, intermediate portions and side surfaces having been set therein by having applied to the leather a liquid polymeric composition comprising a thermosetting resin so that said resin penetrates into said leather; said loop having been subjected to heat as Well as the simultaneous application of pressure while upon an elongated tapered form; said form being tapered on both ends converging downwardly conforming respectively to the position of a loom picker stick in forward and rear positions; and said form having substantially flat vertical sides joining said ends; whereby a tough check strap, resistant to moisture and possessing improved wear and improved friction characteristics is produced having tapered ends accommodating a picker stick in forward and rear positions.

2. The check strap set forth in claim 1, wherein said loop includes multiple strips of natural leather with conforming tapered ends, a splice formed by overlapping and applying adhesive to the conforming tapered ends; at least one such strip being secured within another such strip with the splices spaced on opposite sides of the loop so that the entire outer surface of said one strip is bonded to the entire inner surface of said another with the splices spaced on opposite sides of the loop.

' 3. The check strap set forth in claim 1, wherein said resin is applied to the natural leather before the application of heat and pressure and distributed substantially throughout the leather, and wherein a substantial amount of stretch is removed from the leather by said pressure forcing the loop upon the form.

4. The check strap set forth in claim 2, wherein said means securing is adhesive extending entirely across said outer surface and said inner surface and is the sole means for securing said thicknesses, and wherein said resin extends substantially uniformly throughout the leather forming a unitary check strap.

5. The check strap set forth in claim 4, wherein said resin is polyurethane.

References Cited UNITED STATES PATENTS JAMEs QHI, Primary Examiner 

